Electrical Wiring Question for Fuel Send Unit

[HighTrim]

Morning All,

I just installed a new fuel sending unit on my built in tank. I see that the red wire goes directly from the top of the sending unit screw to the sender connector on the gauge. Now the ground wire, does it run off the unit, split, then one end to a ground, and the other to the bulb connector on the guage?? Do I actually screw in a ground somewhere, or tap into an existing ground wire in the area? My directions for this are hazy at best. Also there is a grounding staple on the washer for the sending unit. Does it matter if the flat side of the staple is against the tank or flange of unit? My holes seem to line up better when the flat side of the staple is against the tank, but that way there doesnt seem to be a whole lot of contact against the flange. Ty each and all for your input.

 

[Texasmark]

Re: Electrical Wiring Question for Fuel Send Unit

Looks like this slipped by without any answers.

Fuel sending systems are nothing more than a variable resistance and a current indicator. 12v is connected across the meter and the sending unit resistor which are wired in series.

The resistance is a function of float (hence wiper) position. The resistance will go from 30-60 thereabouts ohms at one extreme and 250 give or take on the other extreme. The low resistance will make the meter (gauge) deflect fully, while the high resistance will not allow it to deflect....maybe just a tad to show you it is working.

I don't remember which direction is which but that's not important. Once you hook it up it will take just a second to see which way it works by moving the float arm up and down.

The interconnect senario is that you need 12V from the ignition switch ACC terminal, so that no power is applied when the ign sw is OFF (run your battery down). This is applied to one side of the meter.....that terminal may have a + sign marked on it. Doesn't matter, if you get things reversed, the meter will peg in the wrong direction...just reverse wires on the meter.

The other side of the meter is wired to the center contact on your float plate; the one that is insulated from the plate.

The float plate should be hard wired back to the engine run battery - terminal, or a ground buss if you have such a thing.....16 AWG wire is plenty big for this wiring.

Proper operation requires that the float be adjusted for the correct reading on the meter indicating the fuel level in the tank. Bending the float arm, or sliding a screw adjust, for those with such a thing, can be used to obtain the desired results. Usually takes several attempts.

Usually best to set E where you have some fuel left in the tank to get you home in an emergency.

HTH

Mark